<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>BFC解决上下margin重叠</title>
    <style>
        .box1 {
            width: 200px;
            height: 200px;
            background-color: red;
            margin: 100px;
        }

        .box2 {
            width: 200px;
            height: 200px;
            background-color: green;
            margin: 100px;
        }
        .box{
            overflow: hidden;
            /* background-color: gray; */
        }
    </style>
</head>

<body>
    <div class="box">
        <div class="box1"></div>
    </div>
  
    <div class="box2"></div>
</body>

</html>